Introduction
Starting-point plastics and composites calculator for milling, routing, and trimming across ABS, acrylic, PEEK, nylon, CFRP, and GFRP. Use dedicated drilling and turning calculators when the process changes.
How It Works
Enter the planning inputs for this calculator, review the computed output, and compare the result against your machine limits, tooling, material, and shop-floor validation workflow.
Key Formulas
Use the formulas, assumptions, and process notes on this page to validate the result before applying it to a quote, investment case, or live machining setup.
How to Use
Follow the step-by-step guidance, worked examples, and caution notes on the page before locking in the final numbers for production or procurement.
Related Calculators
Use the related calculator links on this page when the current workflow needs a more specific model for speed, feed, cost, capacity, maintenance, or machine selection.
Calculator
Plastics & Composites Speeds & Feeds Calculator 2026
Set a first-pass RPM, chip load, and feed for plastics, composites, and engineering polymers in milling, routing, and trimming workflows. Route drilling and turning to their dedicated calculators before release.
Calculate Plastics Milling, Routing & Trimming Parameters
Direct answer: plastics feeds and speeds must keep chip load high enough to carry heat away. Use this calculator for milling, routing, and trimming thermoplastics, PEEK, Ultem, PTFE, and composites; branch to drilling or turning when the job needs feed-per-rev, breakthrough support, or lathe finish logic.
Page role: plastics heat-control calculator for milling, routing, and trimming after material family, cutter geometry, and dust or chip evacuation method are known.
Plastics & Composites Milling Guide
Search intent around plastics feeds and speeds is usually really about three cutter-driven workflows: milling pockets and profiles, routing sheet stock, or trimming composite edges. That is where this page is strongest. It helps you set a first-pass RPM, chip load, and feed while checking heat risk, chip evacuation, and delamination exposure. Drilling and turning need feed-per-rev logic and should move to their dedicated calculators instead of borrowing these tooth-based outputs.
What This Page Covers Best
First-pass milling, routing, and trimming setups for thermoplastics, engineering polymers, and abrasive composites where chip evacuation and heat management drive the result.
Where It Needs Backup
Drilling and turning need feed-per-rev math, hole-entry or breakthrough rules, and lathe-specific finish logic. Deep-hole composites and bar-stock polymer work should branch out before release.
Best Next Links
Use the carbon-fiber chart, PEEK & Ultem chart, drilling calculator, or turning calculator when the setup leaves this cutter-driven workflow.
Worked Example and Release Boundary
Worked example: PEEK with a 6 mm two-flute carbide cutter at 180 m/min converts to about 9,550 RPM; at 0.04 mm/tooth, feed is about 764 mm/min before heat, fixturing, and edge-quality checks.
Release boundary: keep chip load high enough to make chips, then verify no melting, fuzzing, delamination, dust escape, or workholding lift before production release.
Material Categories
Thermoplastics
Machinability: Good to Excellent
Soften when heated - can melt if cutting parameters are wrong. Use high feed rates to keep chips moving before they re-weld.
- ABS: Excellent, very forgiving
- Delrin/Acetal: Best machinability
- Acrylic: Brittle, prone to cracking
- Nylon: Stringy chips, very tough
High-Performance Polymers
Examples: PEEK, Ultem PEI, PTFE
High temperature resistance, higher cutting forces. PEEK requires slower speeds. PTFE is slippery to fixture.
- PEEK: Aerospace, medical implants
- Ultem: High-temp electrical
- PTFE: Seals, chemical equipment
Fiber-Reinforced (CFRP, GFRP)
Very abrasive, requires diamond tools
Carbon and glass fibers rapidly destroy carbide tools. PCD or diamond-coated tools essential. CFRP dust is a health hazard.
- Use compression routers for edge quality
- Vacuum extraction at the cut zone is mandatory
- Backer material prevents delamination
- Do not release drilling parameters from this page
Thermosets (FR4, Phenolic)
Don't melt - produce dust
Formed through irreversible chemical cure. Produce powder/dust rather than chips. Fiberglass versions are very abrasive.
- FR4/G10: PCB substrates - abrasive
- Phenolic: Brake pads, electrical
- Dust extraction required
Speed Reference
| Material | Milling (m/min) | Routing (m/min) | Tool |
|---|---|---|---|
| Delrin/Acetal | 250-600 | 300-700 | Carbide/ZrN |
| ABS | 200-500 | 250-600 | Carbide/ZrN |
| Acrylic (PMMA) | 150-350 | 180-420 | O-Flute, Single Flute |
| PEEK | 100-280 | 130-340 | Carbide Uncoated |
| CFRP | 80-240 | 100-280 | PCD / Diamond |
| FR4/G10 | 100-280 | 120-300 | Diamond Coated |
Milling and routing values are the primary workflow on this page, and trimming is close enough to use the same calculator model as a first pass. If the job turns into holemaking or lathe work, move to the drilling calculator or turning calculator before you release numbers.
Best Practices
Do
- Keep chips moving with high feed rates
- Use air blast for thermoplastics
- Use sharp, polished cutting edges
- Climb mill for better surface finish
- Use PCD for composites
Avoid
- Don't let chips re-melt onto surface
- Don't use oil coolant on acrylic/PC
- Don't ignore composite dust extraction
- Don't use dull tools
- Don't use milling outputs for drilling or turning
Frequently Asked Questions
On this page, treat the calculator as a plastics milling, routing, and trimming start point. Use high enough feed to keep chips moving, keep tools sharp, use positive geometry, and use air blast or extraction so heat leaves with the chip. Commodity plastics like acetal are forgiving, while acrylic and thin-wall engineering polymers need a lighter touch. If the job turns into drilling or lathe work, switch to the dedicated drilling or turning calculator because feed-per-rev logic changes the safe answer.
Continue The Plastics Workflow
Use these tools when the job branches from plastics milling, routing, or trimming into composite chart lookup, engineering-polymer validation, drilling, or turning.
General Feeds & Speeds
Return to the main CNC feeds and speeds calculator for RPM, feed rate, chip load, SFM, MRR, and power context.
Carbon-Fiber Chart
Quick-reference CFRP, GFRP, and Kevlar routing or trimming windows before setup-specific validation.
PEEK & Ultem Chart
Reference heat windows and chip-load ranges for engineering polymers and filled high-temp plastics.
Drilling Calculator
Switch here for plastics and composite holemaking, feed-per-rev, peck cycles, and breakthrough control.
Turning Calculator
Use lathe-specific feed-per-rev and finish logic for bar-stock PEEK, PTFE, nylon, and other polymers.
Calculator trust notes
Formula and validation boundary
plastics-feeds-speeds is a planning tool. Use the result after checking the formula scope, source boundaries, and shop-floor calibration inputs below.
Formula basis
Uses surface-speed conversion, spindle RPM, flute count, chip load, tool geometry, coating, operation, and material factors to produce starting cutting parameters.
Model boundary
Planning-level feeds and speeds. Outputs are starting points that must be validated against machine rigidity, toolholder, coolant, engagement, and manufacturer recommendations.
Validate with
- Machinery's Handbook or equivalent machining formula reference
- Cutting-tool manufacturer technical guidance for parameter ranges
Primary units: mm, inch, RPM, SFM, m/min, mm/min, IPM
Core outputs: spindle speed, feed rate, chip load, surface speed, depth of cut, warnings
Calibration loop
For repeat use, save the input assumptions, source used, output values, measured result, and variance note. Compare the next real job, trial cut, quote review, service record, or finance result against the calculator record before changing the standard.
Track outputs: spindle speed, feed rate, chip load, surface speed, depth of cut, warnings.
Shop release checks
Before using these results for a quote, program, or capital case, verify machine limits, toolmaker data, measured load, and first-article results against the same assumptions shown here.
- Machine constraint: spindle speed, torque, axis feed, duty cycle, fixture rigidity, and coolant capability.
- Source constraint: OEM manuals, toolmaker charts, service records, finance policy, or tax guidance for the modeled case.
- Measured proof: load meter, cycle study, first article, CMM report, or accounting record that confirms the assumption.
- Change control: rerun the calculator when material, tool geometry, utilization, cost rate, or maintenance interval changes.